Method of producing vanillin from waste sulphite liquor



Nov. 16, 1937.

R. S. HATCH METHOD OF PRODUCING VANILLIN FROM WASTE SULPHITE LIQUOR Filed June 27, 1936 IA/N REACTION CHAMBER I-IEATEXCHA M65 //0 PRESSURE REG-UL! T0 R 17516 T ION PAODUC 7 L /3 nusr: suL PH/Tt' L/Q (10!? AND ALKALINE REAGENT;

INVENTOR BY 24A ATTORNEY Patented Nov. is, 193.1 1 299mm UNITED STATES PATENT OFFICE METHOD OF PRODUCING VANILLIN FROM WASTE SULPHITE LIQUOR Raymond S. Hatch, Longview, Wash, assignor to Weyerhaeuser Timber Company, Tacoma, Wash, a corporation of Washington Application June 27, 1936, Serial No. 87,809 6 Claims. (01. 260-137) This invention relates to the production and action, minimum hydrogen ion concentration or recovery of vanillin from waste sulphite liquor about. pH 13. Any excess ofalkali over the and particularly to improvements in the efficiency amount required is merely wasted. The temand economy of the reaction of waste sulphite perature of the reaction is also relatively low, and

5 liquor with alkaline agents to efiect the commerthe time particularly is limited so that useless cial recovery of vanillin therefrom. application and waste of heat, which is com- Since the announcement by Kiirschner in 1928 paratively expensive, is avoided. Pressures-above of the possibility of producing vanillin from waste atmospheric are utilized, but excessive pressures sulphite liquor, various investigators have from are avoided, and the apparatus necessary is thus 0 time to time studied the reaction under different simplified and is correspondingly inexpensive.

conditions. A review of the literature on the The invention will bebetter understood by refsubject, as well as a report of their own study erence to the following specification and the acis given by G. H. Tomlinson and Harold Hibbert companying drawing, in which the figure is a in Journal of the American Chemical Society, diagrammatic illustration of an apparatus which 5 Vol. 58, No. 2, pages 345 and 348. u may be employed practically in the operation of It is well established that vanillin can be prothe process. duced by heating waste sulphite liquor with an Referring to the drawing, 5 indicates the realkaline agent for extended periods at atmosaction chamber which may be supplied with a pheric or elevated pressures. Previously, howsuitable heating agent, for example steam,

ever, relatively high concentrations of the alkathroug a P p T e c nsate a d unconline agent (about 240 grams of caustic soda per densed steam may be withdrawn through the liter of waste sulphite liquor) have been used, pipe I. Since the temperature to be maintained and the time of heating at atmospheric pressure s in t e e g bo ood of C-, t e heating has varied from 6 to 20 hours. At higher presmay be effected readily with steam at relatively g5 sures, some reduction of the time of treatment low pressures. Within the reaction chamber 5 has been eifected, as for example, 4 hours at 6 is a coil 8 to afford a heat transfer surface of atmospheres. The relatively high quantity of relatively large size, through which the reacting alkaline reagent, and particularly the heat conmaterials are forced. As the reacting materials sumption, has prevented any practical commerfiow through the coil or coils and are subjected 3o cial development based upon the process because to heat by exchange with the steam in the rethe yield of vanillin is low and the process is action chamber, the desired reaction products entirely too costly to permit operation on an escape through a pipe 9 to an exchanger 10 eneconomic basis. The high cost of equipment, closing a series of tubes ll terminating in champarticularly if substantial pressures are used, has bers l2 and I3 at the ends of the exchanger.

also tended to prevent commercial application of The reaction products surround the tubes l I car- 35 the process. rying the incoming materials which are thereby It is the object of the present invention to raised to a temperature approaching that atafiord a simplified and commercially practical tained' in the coil 8. The length of the coil, procedure utilizing quantities of alkaline agents or coils if more than one are used, and of the 40 and heat sufficiently low to permit economic optubes II, is such as to permit retention of the 40 eration. It has been found that the optimum reaction materials in the heating zone for a yield of vanillin issecured under these condiperiod of approximately 15-30 minutes. The retions, and that consequently commercial appliaction products are withdrawn through a pipe cation of the process is feasible. x l4, after which they may be subjected to treat- In carrying out the invention, the reacting ment by known methods to extract the vanillin 45 materials are heated in such a way as to permit therefrom. A pressure relief valve l4 in the continuous introduction thereof withcontinuous pipe l4 controls the pressure within the system. withdrawal of the reaction products and the It should be set for a pressure slightly higher most efiective application of heat during the rethan the pressure of saturated steam at the action, with the minimum loss of heat through temperature maintained. 50 the withdrawal of products -of the reaction. The mixture of waste sulphite liquor with the Furthermore, the alkaline agents are added in required amount of alkaline reagent is introamounts relatively low as compared to the duced through a pipe I5 to the chamber l3 at amounts heretofore considered necessary and one end of the exchanger l0, and passes through 66 suflicient only to ensure, at the end of the rethe tubes II- to the chamber l2 at the other end of the exchanger. In this passage, the enterreaction chamber.

ing material absorbs heat from the reaction products, the latter escaping at relatively low temperatures while the incoming material is preheated to approximately the temperature of the reaction. The incoming material is delivered through a pipe IE to the coil or coils 8 of the The use of the heat exchanger avoids waste of heat and ensures the introduction of the incoming material to the reaction chamber at a temperature at which it will readily absorb additional heat to effect the desired reaction in the shortest practicable period.

For the purpose of the invention I may employ as an alkaline agent, the hydroxides of the alkali metals, preferably sodium or potassium hydroxide. The amount of reagent employed is the minimum amount which will maintain hydrogen'ion concentration of substantially pH 13 at the'end'of the reaction. From 35 to 40 grams per liter of sodium hydroxide is usually sufiicient, or the equivalent amount of potassium hydroxide. The best results have been obtained at 200 C. with about 40 grams per liter of sodium hydroxide in the waste liquor; The mixture thus prepared is pumped or otherwise forced through the apparatus previously described, being introduced through the pipe I5. I have found that a pressure of approximately 215 pounds is satisfactory. Temperatures between 180 and 220 C. are desirable. Obviously, the amount of the alkaline agent and the temperature and pressure may be varied, but within the limits "mentioned the optimum yield of vanillin is obtained. Substantially no gas is formed during the reaction, and therefore the pressure within the system will be that which corresponds to saturated steam pressure at the operating temperature.

As an example of the practical application of the invention. I may add 35-40 grams per liter of sodium hydroxide or the equivalent amount of potassium hydroxide. The mixture is introduced at a pressure of approximately 215 pounds to the apparatus hereinbefore described, and heated to a temperature of about 200 0., the operation being regulated so that the reacting materials are heated for a period of about 15 to 30 'minutes. The reaction product escapes, after passing through the heat exchanger, at relatively low temperature and may be subjected thereafter to suitable treatment to recover the vanillin therefrom.

The process as described is commercially practicable and capable of producing vanillin from waste sulphite liquor on an economic and profitable basis. So far as I am aware, none of the processes heretofore suggested has produced comparable yields at costs which permit commercial development and practical application of the reaction of waste sulphite liquor with alkaline reagents.

Various changes may be made in the details of procedure and in the apparatus employed therein the liquor an alkaline agent in an amount sufficient to afiord at the conclusion of the reaction a pH of about 13, and heating the mixture to a temperature of from C. to 220 C. for a period not exceeding thirty minutes.

2. The process of producing vanillin from waste sulphite liquor which comprises adding to the liquor an alkaline agent in an amount sufficient to afford at the conclusionof the reaction a pH of about 13, and heating the mixture at a temperature of approximately 200 C. for a period of about fifteen minutes.

3. The process of producing vanillin from waste sulphite liquor which comprises adding to the liquor an alkaline agent in an amount sufilcient to afford at the conclusion of the reaction a pH of about 13, and heating the mixture to a temperature of approximately 200 C. for a period of about fifteen minutes while it is maintained under a pressure of about 215 pounds per square inch. i r

4. The process of producing vanillin from waste sulphite liquor which comprises adding to the liquor an alkaline agent in an amountfsuihcient to afford at the conclusion of the reaction a pH of about 13, and heating the mixture to a temperature of from about 180 C. to 220 C. for a period of from about fifteen to thirty minutes, while it is under a pressure of about 215 pounds per square inch. I

5. The process of producing vanillin from waste sulphite liquor which comprises adding to the liquor an alkaline agent in an amount sufllcient to afford at the conclusion of the reaction a pH of about 13, heating the mixture to a tempera-' ture of approximately 200 C. for a period of about 15 minutes, and immediately thereafter cooling the product.

6. The process of producing vanillin from waste sulphite liquor which comprises adding to the liquor an alkaline agent in an amount suflicient to aflord at the conclusion of the reaction a pH of about 13, heating the mixture to a temperature of from 180 C. to 220 C. for a period not exceeding thirty minutes, and immediately thereafter cooling the product.

RAYMOND S. HATCH. 

